Eye Contact - It is normal and usually encouraging for the listener to look at the speaker. Eye contact can however be intimidating, especially for more shy speakers – gauge how much eye contact is appropriate for any given situation. Combine eye contact with smiles and other non-verbal messages to encourage the speaker.
Posture - Posture can tell a lot about the sender and receiver in interpersonal interactions. The attentive listener tends to lean slightly forward or sideways whilst sitting. Other signs of active listening may include a slight slant of the head or resting the head on one hand.
Mirroring - Automatic reflection/mirroring of any facial expressions used by the speaker can be a sign of attentive listening. These reflective expressions can help to show sympathy and empathy in more emotional situations. Attempting to consciously mimic facial expressions (i.e. not automatic reflection of expressions) can be a sign of inattention.
Distraction - The active listener will not be distracted and therefore will refrain from fidgeting, looking at a clock or watch, doodling, playing with their hair or picking their fingernails.